Jump to content
Sign in to follow this  

Race Gas?

Recommended Posts

I looking at putting a new piston in my 600R. I've been looking around, I can get it 9-1, 10.5-1, and 11-1. My question is, how high can I go before needing race gas. Or some kind of mix. I know I can run 9-1, but what about 10.5-1. I like running pump gas for when I'm ridding in the back woods and race gas in unavailable. Thanks for any info.

Share this post


Link to post
Share on other sites

you can probaly get away with 10.5 to 1 with out race gas. But make sure you jet really good and a little on the rich side. 11 to 1 you will need to run race gas or a mixture. Yeah 10.5 to 1 will be fine on pump gas.

Share this post


Link to post
Share on other sites

Thanks. I had a thought that 10.5-1 would work, but didn't know for sure.

Share this post


Link to post
Share on other sites

Im wondering the same thing with my 650R, its either stock 10:5 11:1 11:5 or 12:1 It would be great to do the 12:1 but i cant afford to run gas at $8-$10 a gallon. I proble cant go over 10:5 without running race gas.

Share this post


Link to post
Share on other sites
Im wondering the same thing with my 650R, its either stock 10:5 11:1 11:5 or 12:1 It would be great to do the 12:1 but i cant afford to run gas at $8-$10 a gallon. I proble cant go over 10:5 without running race gas.

No you cant go over 10.5:1 Compression with out using a mixture of race gas or strait race gas. You can go to the 11:1 but you ill need to jet so perfect and any slight mistake 👍 , you will burn up the piston. Not worth it! Unless you ill run race gas! I would run it safe and get the 10.5:1.

Share this post


Link to post
Share on other sites

question on the 10.5:1...

say ur out in bumflock...and there's only regular, will the octain boosters get u by???👍

r they basically high priced race gas in a bottle or sumtin special??? :worthy:

:busted:

Share this post


Link to post
Share on other sites
question on the 10.5:1...

say ur out in bumflock...and there's only regular, will the octain boosters get u by???👍

r they basically high priced race gas in a bottle or sumtin special??? :worthy:

:busted:

octane booster doesn't boost your octane much. for what they recommend. it might take 91 to 92

the higher the octane the cooler your bike will run.

why can't your run anything higher than a 10.5:1 piston without using high octane.

yz250f's come stock with 13.5:1 pistons now and they run perfectly find off of 91

???

Share this post


Link to post
Share on other sites
question on the 10.5:1...

say ur out in bumflock...and there's only regular, will the octain boosters get u by???👍

r they basically high priced race gas in a bottle or sumtin special??? :worthy:

:busted:

I am not familiar with octane boosters. But I suppose, if it says that it will boost the octane level I guess it will. It would probaly work but I am not a 100% on that.

Share this post


Link to post
Share on other sites
octane booster doesn't boost your octane much. for what they recommend. it might take 91 to 92

the higher the octane the cooler your bike will run.

why can't your run anything higher than a 10.5:1 piston without using high octane.

yz250f's come stock with 13.5:1 pistons now and they run perfectly find off of 91

???

I think the air cooled oil cooker L engine would do fine with 11:1 IF it's kept cool. An oil cooler would probably be necessary. Using 91.

With 87, I think the problem would be lots of pinging in certain conditions.

Share this post


Link to post
Share on other sites
I think the air cooled oil cooker L engine would do fine with 11:1 IF it's kept cool. An oil cooler would probably be necessary. Using 91.

With 87, I think the problem would be lots of pinging in certain conditions.

sorry, I meant, why would this engine ping using 91 pump gas if it has more than 10.5:1 . because they are using much more aggressive mapping and higher compression on other engines and they run fine on 91. <-- thats my question. sorry for the misunderstanding

also, if you use 60 weight amsoil engine oil. it should keep your bike running cooler

Share this post


Link to post
Share on other sites

The YZ250F is a completely different engine. It's water cooled, has a smaller bore, better chamber, a higher operating rpm range, and it has three-dimensional ignition mapping using load and rpm. All of those work toward reducing the octane requirements of the engine. Another example is the CBR600F4i with 12.5:1 compression and it runs just great on 87.

The XR600 has a big open chamber with zero quench, cylinder head temps are much higher because it's air cooled, the bore is huge, it has a low basic operating rpm, and only rpm-based ignition mapping. That's why the airhead bikes are sensitive to octane.

To answer BigOne's question, 10.5:1 compression seems to be approaching the edge of practicality for 91 octane pump gasoline.....especially since so many people seem to have less-than-perfect jetting in their bikes.

One word on octane boosters: they are an utter waste of money. For $7 you get a 16oz bottle of something that is maybe 110 octane. Mix that with 4+ gallons of your all-that-was-available-in-East-Podunk 87 and you will be lucky to end up with a tank of 87.2 octane fuel.

On a side note as an FYI, octane in and of itself does not dictate the energy content of a fuel, how hot it burns, or how fast it burns.

Share this post


Link to post
Share on other sites

If I am not mistaken, "octane" is the measure of how much the gas can be compressed before it self combusts. For instance, 87 is more volatile than 91 will explode sooner, octane booster is a chemical that makes gasoline less volatile, it is not race gas and it does work, just buy a good brand like Pennzoil and it will work fine. Whenever I can't get my hands on premium I run regular with octane booster and have not had a problem yet, in fact just from the seat of my pants I think my bike runs stronger on regular and octane booster.

Share this post


Link to post
Share on other sites

Excluding volatility, I suppose that is the gist of it, but the thorough explanation is still far more complicated. Volatility, in the context of gasoline chemistry, refers more to aromatic hydrocarbons with high vapor pressures and often high octane ratings.

Share this post


Link to post
Share on other sites
Excluding volatility, I suppose that is the gist of it, but the thorough explanation is still far more complicated. Volatility, in the context of gasoline chemistry, refers more to aromatic hydrocarbons with high vapor pressures and often high octane ratings.

Oh i see, I meant that lower octane gas explodes at lower pressure, so it is less stable or more volatile. But in the sense of the energy contained inside the lower grade is less volatile.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Reply with:

Sign in to follow this  

×
×
  • Create New...